Extended Depth-of-Field Camera

What is an extended depth-of-field camera?

Depth of field refers to the range of distance over which a subject appears in-focus in a photographic image. An extended depth-of-field camera extends the depth of field without sacrificing resolution or brightness, making it possible to clearly capture a subject without adjusting interval and angle between subject and camera. Scenes that used to require multiple cameras or readjusting focus can now be captured at once with a single camera. Because components for focus adjustment are no longer necessary, our extended depth-of-field camera has excellent stability and reliability. Further, a compact machine vision can be realized, enabling applications in a variety of fields such as factory automation (FA), distribution, security, and personal applications.

Ricoh extended depth-of-field camera features

Our extended depth-of-field camera comprises a specialized lens and a specialized camera with a built-in image processor. Depth-of-field can be extended with a typical camera by using a smaller aperture, but the image becomes darker. With our camera, the depth-of-field can be extended while maintaining brightness. This is realized by a combination of a uniquely designed specialized lens and image processing by an IC built in the camera body. We have a lineup of specialized lenses with various focal lengths (such as 8.5mm, 12mm, and 35mm). We also provide different types of specialized cameras with 2M and VGA resolutions, for example.

Extended depth-of-field camera applications

Usage scenario 1: foreground and background imaging

Whereas capturing subjects in both the foreground and the background previously involved multiple cameras or altering the position of the camera, it is now possible to keep both the foreground and the background in focus without focus adjustment. As a result, our cameras can be utilized for QR code recognition and object recognition on moving production lines, for example. To capture subjects separated in the field by a range of several tens of centimeters, for example, the combination of a specialized lens with an 8mm focal length and a specialized VGA camera is ideal.

Figure 1: Usage scenario for capturing subjects at different depths

Imaging result from conventional camera.Front QR code is unreadable.

Imaging result from extended depth-of-field camera.Both front and rear QR codes are readable.

Usage scenario 2: capturing oblique subjects

Whereas capturing oblique subjects previously required multiple cameras or focus adjustment, it is now possible to keep an oblique subject entirely in focus without focus adjustment. As a result, multiple images no longer need to be connected together after separately capturing near and distant portions of a subject. Instead, information on the entire subject can be captured in a single shot. Potential applications include OCR and substrate inspection. To capture subjects separated in the field by a range of several centimeters, for example, the combination of a specialized lens with 35mm focal length and a specialized 2M camera is ideal.

Figure 3: Usage scenario for capturing an oblique subject

Imaging result from conventional camera.
Front side of 50 pin connector is out of focus.
Component number is out of focus.

Imaging result from extended depth-of-field camera.
Both 50 pin connector and component number are in focus.

Usage scenario 3: capturing subjects at different heights and depths

Whereas capturing subjects at different heights and depths previously involved multiple cameras or change of vertical position of the camera, it is now possible to keep multiple subjects at different heights and depths in focus without focus adjustment. Potential applications include object recognition on moving production lines for products of different heights and depths, and image recognition in cases where printed matter is progressively stacked higher.

Figure 5: Usage scenario for capturing subjects at different heights

To capture subjects separated in the field by a range of several centimeters, such as imaging inside a can as shown in Figure 6, for example, the combination of a specialized lens with 8mm or 12mm focal length and a specialized 2M camera is ideal.

Photographing environment
(Side view of can and camera)

Imaging result from extended depth-of-field camera
Imaging inside of a can, near side all through rear side is in focus.

Imaging result from conventional camera
Imaging inside of a can, near side (edge of the can) is in focus and rear side (bottom of the can) is out of focus.